FURTHER STUDIES ON RHESUS MONKEYS IMMUNIZED AGAINST SCHISTOSOMA JAPONICUM BY ADMINISTRATION OF X-IRRADIATED CERCARIAE
In preliminary experiments performed on mice to determine the critical doses of x irradiation, mice were inoculated with irradiated Schistosoma japonicum cercariae which had been exposed to 2000, 10,000, 30,000, 45,000, and 60,000 r. Autopsy on the 35th day after inoculation showed the presence of immature worms in the group of mice which received 2000 r, but no worms in the other groups. In other mice inoculated with irradiated cercariae exposed to 500, 1200, and 1700 r, autopsy on the 35th day after inoculation showed that in the 500-r group, mature worms and eggs were found. In the 1200-r group, male worms with testes and female worms with ovaries but without eggs were found. In the 1700-r group one mouse harbored one male worm with testes, but 13 others had only immature worms. In the 3rd series, mice were infected with 50 male and 50 female cercariae exposed to 1700 r. More male than female worms were recovered, although equal numbers had been inoculated; furthermore, 83.6% of male worms had developed testes but only 8.7% of female worms possessed ovaries. Apparently, x irradiation is more harmful to the development of female than male worms. Fourteen monkeys were immunized with x irradiated cercariae before being challenged. The doses of 250-kv x rays varied from 1700 to 4000 r and the number of immunizing inoculations was either 3 or 4 at intervals from 27 to 106 days. The mean number of eggs/g of stool per day during the first 30 days in the immunized monkeys varied from 0 to 924 and in nonimmunized from 1220 to 46,036. The number of normal adult female worms recovered from immunzied monkeys varied from 0 to 43 and and in nonimmunized from 131 to 156. Generally, inoculations of monkeys with irradiated cercariae of the human strain of S. japonicum gave marked protection against a subsequent challenge with the homologous strain. Cercariae exposed to 1700 to 3000 r were almost equally effective in producing an immunizing effect, while those exposed to 3500 to 4000 r were somewhat less effective. The effect of 1700 r on cercarial sterility was not completely predictable, and 2000 r did not leave a good margin of safety. Therefore, for vaccination, S. japonicum cercariae should be irradiated with 2500 or 3000 r. Three or 4 inoculations were equally effective in producing resistance. The results showed that in the immunized rhesus monkeys both eggs and worms of the challenge infection of S. japonicum are substantially reduced in number due to the induced immunity of the irradiated cercariae. The effects of the immunization seemed to vary with the dose of x irradiation to cercariae, number of immunizing inoculations, number of immunizing cercariae, time interval between immunizing inoculations, and the time of challenge. It is suggested that with the proper adjustment of these factors, a state of absolute resistance to the challenge infection of S. japontcum in rhesus monkeys may be reached. This goal is believed to be reasonable and proper even though the immune effect produced by giving irradiated cercariae of S. mansoni to mice is at variance in centain respects with some of these results. (BBB)
- Research Organization:
- State Univ. of Iowa, Iowa City
- NSA Number:
- NSA-18-015890
- OSTI ID:
- 4068123
- Journal Information:
- Zeitschrift fuer Tropenmedizin und Parasitologie (West Germany), Vol. Vol: 14; Other Information: Orig. Receipt Date: 31-DEC-64
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
Similar Records
HISTOPATHOLOGY IN ALBINO MICE AND RHESUS MONKEYS INFECTED WITH IRRADIATED CERCARIAE OF SCHISTOSOMA JAPONICUM
Vaccination against bovine schistosomiasis japonica with highly X-irradiated schistosomula